fix: properly load field metadata from a table with identity columns

Fixes #2152

crates/core/src/kernel/models/schema.rs

@@ -25,6 +25,8 @@ pub enum MetadataValue {
     Number(i32),
     /// A string value
     String(String),
+    /// A Boolean value
+    Boolean(bool),
 }
 
 impl From<String> for MetadataValue {
@@ -45,6 +47,12 @@ impl From<i32> for MetadataValue {
     }
 }
 
+impl From<bool> for MetadataValue {
+    fn from(value: bool) -> Self {
+        Self::Boolean(value)
+    }
+}
+
 impl From<Value> for MetadataValue {
     fn from(value: Value) -> Self {
         Self::String(value.to_string())
@@ -184,6 +192,7 @@ impl StructField {
         let phys_name = self.get_config_value(&ColumnMetadataKey::ColumnMappingPhysicalName);
         match phys_name {
             None => Ok(&self.name),
+            Some(MetadataValue::Boolean(_)) => Ok(&self.name),
             Some(MetadataValue::String(s)) => Ok(s),
             Some(MetadataValue::Number(_)) => Err(Error::MetadataError(
                 "Unexpected type for physical name".to_string(),
@@ -850,4 +859,11 @@ mod tests {
             Invariant::new("a_map.value.element.d", "a_map.value.element.d < 4")
         );
     }
+
+    /// <https://github.com/delta-io/delta-rs/issues/2152>
+    #[test]
+    fn test_identity_columns() {
+        let buf = r#"{"type":"struct","fields":[{"name":"ID_D_DATE","type":"long","nullable":true,"metadata":{"delta.identity.start":1,"delta.identity.step":1,"delta.identity.allowExplicitInsert":false}},{"name":"TXT_DateKey","type":"string","nullable":true,"metadata":{}}]}"#;
+        let schema: StructType = serde_json::from_str(buf).expect("Failed to load");
+    }
 }

crates/core/src/lib.rs

@@ -676,4 +676,13 @@ mod tests {
             DeltaTableError::InvalidTableLocation(_expected_error_msg),
         ))
     }
+
+    /// <https://github.com/delta-io/delta-rs/issues/2152>
+    #[tokio::test]
+    async fn test_identity_column() {
+        let path = "../test/tests/data/issue-2152";
+        let _ = crate::open_table(path)
+            .await
+            .expect("Failed to load the table");
+    }
 }

crates/test/tests/data/issue-2152/_delta_log/00000000000000000000.json

@@ -0,0 +1,3 @@
+{"commitInfo":{"timestamp":1706770085847,"operation":"CREATE TABLE","operationParameters":{"partitionBy":"[]","description":null,"isManaged":"true","properties":"{}","statsOnLoad":false},"isolationLevel":"WriteSerializable","isBlindAppend":true,"operationMetrics":{},"tags":{"restoresDeletedRows":"false"},"engineInfo":"Databricks-Runtime/14.1.x-photon-scala2.12","txnId":"5ba2d1f4-09e0-4013-920a-92b057185128"}}
+{"metaData":{"id":"7791991a-60e9-4a8f-bff0-ccffec779dc4","format":{"provider":"parquet","options":{}},"schemaString":"{\"type\":\"struct\",\"fields\":[{\"name\":\"ID_D_DATE\",\"type\":\"long\",\"nullable\":true,\"metadata\":{\"delta.identity.start\":1,\"delta.identity.step\":1,\"delta.identity.allowExplicitInsert\":false}},{\"name\":\"TXT_DateKey\",\"type\":\"string\",\"nullable\":true,\"metadata\":{}}]}","partitionColumns":[],"configuration":{},"createdTime":1706770085202}}
+{"protocol":{"minReaderVersion":1,"minWriterVersion":6}}